Hinge apparatus for cover of image forming apparatus

ABSTRACT

A hinge apparatus for a cover of an image forming apparatus has a hinge body with supporting brackets, movably inserted into a coupling hole positioned in a main body of the image forming apparatus, a hinge cam connected to the cover and pivotably connected to the supporting brackets, and a pressure device disposed at the hinge body to press the hinge cam. Accordingly, the hinge apparatus can be implemented with a simple and easy assembly operation, since it is not a complicated structural connection among the component parts of the hinge apparatus.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No. 12/213,867 filed on Jun. 25, 2008 now U.S. Pat. No. 7,665,183 in the U.S. Patent and Trademark Office, which is a continuation of U.S. patent application Ser. No. 10/757,999 filed on Jan. 16, 2004 in the U.S. Patent and Trademark Office (U.S. Pat. No. 7,406,747 issued Aug. 5, 2008). This application claims the priority benefit of U.S. patent application Ser. No. 12/213,867 filed Jun. 25, 2008, the priority benefit of U.S. patent application Ser. No. 10/757,999 filed Jan. 16, 2004, and the priority benefit of Korean Patent Application No. 2003-27806, filed Apr. 30, 2003 in the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a hinge apparatus, and more particularly to a hinge apparatus that supports a cover of an image forming apparatus, such as a photocopier, a scanner, or a multifunction machine, so that the cover thereof pivotably opens and closes.

2. Description of the Related Art

An image forming apparatus, which has document scanning function like a photocopier, a scanner, or a multifunction machine, scans a document, then stores a scanned image as data, or prints the image on a printing paper. Such an image forming apparatus includes a document glass disposed on a main body of the image forming apparatus to scan the document, a cover to secure the document laid on the document glass, and a hinge apparatus connecting the cover and the main body of the image forming apparatus.

FIG. 1 shows a hinge apparatus 30 to open and close the cover of the conventional image forming apparatus 10, disclosed in Japanese Patent Publication No. 11305358. As shown in FIG. 1, the conventional hinge apparatus 30 includes a hinge body 32 integrally formed with a spring pin 31, and a spring 33 connected to the spring pin 31 at one end. A cover 20 is provided with a hinge pin 21 that is inserted into a long hole 32 a positioned in the hinge body 32. The spring 33 is connected to the hinge pin 21, and therefore, the cover 20 and the hinge apparatus 30 form a set. A cam part 20 a, which is disposed at the cover 20, is in tight contact with the hinge body 32 under a recovery force of the spring 33. Furthermore, the hinge body 32 is disposed to move upward and downward within a coupling hole 10 a positioned in the main body of the image forming apparatus 10.

The conventional image forming apparatus with the above structure has a document glass 11, which is exposed and covered through pivoting of the cover 20 centering on the hinge pin 21. The cover 20 opens and closes slowly, since the cover 20 is moved with the cam part 20 a of the cover 20 being in close contact with the hinge body 32. Moreover, when a thick document is laid upon the document glass 11, the hinge body 32 is lifted upward to a predetermined height, so that the cover 20 uniformly presses the document, such as a thick book, laid upon the document glass 11.

But in the above conventional hinge apparatus 30, there is a difficulty in assembling the cover 20 and the hinge apparatus 30, since the both ends of the spring 33 are directly connected with the cover 20 and the hinge body 32, that are respectively at an opposite side. In other words, the spring 33 has a high elastic modulus to secure a slow opening and closing of the cover is used, and accordingly it is not easy to connect the spring 33 with the spring pin 31 of the hinge apparatus 30 and with the hinge pin 21 of the cover 20.

Also, a friction between the cam part 20 a of the cover 20 and the hinge body 32 generates a noise in opening and closing of the cover 20. Another problem is that the hinge body 32 can be released out of the coupling hole 10 a of the main body of the image forming apparatus, when a thick document is being scanned.

SUMMARY OF THE INVENTION

The present invention has been made to solve the aforementioned problems. Accordingly, an aspect of the present invention is to provide a hinge apparatus for a cover of an image forming apparatus, which is assembled with ease and decreases a noise occurring in opening and closing the cover.

To achieve the above and/or other aspects of the present invention, a hinge apparatus for a cover of the image forming apparatus is provided. The hinge apparatus opens and closes the cover of the image forming apparatus, and pivotably connects a main body of the image forming apparatus with the cover, to expose and cover a document glass. The hinge apparatus has: a hinge body, movably inserted in a first direction into a coupling hole positioned in the main body of the image forming apparatus, and having supporting brackets; a hinge cam, of which one side is connected to the cover, and pivotably connected to the supporting brackets; and a pressure device disposed at the hinge body to press the hinge cam.

According to one aspect, a housing chamber is provided within the hinge body, and the pressure device has: a pusher disposed in the housing chamber, that protrudes out of the housing chamber; and a spring disposed within the housing chamber to press the pusher.

According to one aspect, the hinge cam has a body portion connected to the cover, and a cam part pivotably connected to the body in close contact with the pressure device.

According to one aspect, each of the supporting brackets and the cam part is provided with a shaft hole, and the hinge apparatus additionally has a hinge shaft inserted through the respective shaft holes, to pivotably connect the cam part with the supporting brackets.

According to one aspect, a center of the hinge shaft is located toward the document glass compared to a pressure central line of the pressure device.

According to one aspect, the pusher has a locking protrusion, the hinge body is provided with a guide slot, and the locking protrusion is inserted into the guide slot, and prevents the release of the pusher from the hinge body.

According to one aspect, the hinge body has, a first protrusion positioned at one side of the hinge body, to prevent the supporting brackets from entering the coupling hole.

According to one aspect, the main body has: a hooking portion positioned at the lower part of the main body of the image forming apparatus; and, the hinge body has a second protrusion positioned at a first side of the hinge body, that is caught by the hooking portion, which prevents the release of the hinge body from the coupling hole when the hinge body is moved in a direction opposite the first direction.

According to one aspect, at least one of the pusher and the hinge cam is made of a lubricating resin.

Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and/or advantages of the present invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:

FIG. 1 shows a cross sectional view of a conventional hinge apparatus to open and close a cover of an image forming apparatus;

FIG. 2 shows an exploded perspective view of a hinge apparatus to open and close a cover according to an embodiment of the present invention;

FIG. 3 shows a view of the hinge apparatus of FIG. 2 connected to the cover of the image forming apparatus after assembly; and

FIGS. 4 through 7 show cross sectional views, to describe an operation of the hinge apparatus of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below to explain the present invention by referring to the figures.

Referring to FIGS. 2 and 3, a hinge apparatus 100 to open and close a cover 50 of an image forming apparatus 40, according to an embodiment of the present invention, includes a hinge body 110, a pressure device 120, and a hinge cam 130.

The shown embodiment of the hinge body 110 has a configuration of a hexahedron box, of which an interior is void and one side is opened, and is received in a coupling hole 40 a positioned in a main body of the image forming apparatus 40, to be moved upward and downward. A housing chamber 111 is provided inside of the hinge body 110, and at one side of the housing chamber 111, an open portion 111 a is positioned to communicate with an exterior. It is understood, however, that the hinge body 110 can have other configurations that the shown hexahedron box.

Furthermore, a pair of supporting brackets 113 extended from sidewalls of the hinge body 110, and are positioned at sides of the open portion 111 a. Each of the supporting brackets 113 supports the hinge cam 130 and has a shaft hole 113 a therein. At the sidewalls of the hinge body 110, guide slots 112 a are positioned to guide an upward and downward movement of the pressure device 120.

Also, on each of a front wall 114 and a rear wall 115 of the hinge body 110, that are connected with the sidewalls, a first protrusion 116 is positioned to protrude outward, thereby restricting the inserting range of the supporting brackets 113 into the coupling hole 40 a. The first protrusions 116 are located at lower parts of the supporting brackets 113. When the hinge body 110 is inserted into the coupling hole 40 a, the first protrusions 116 are caught at the main body of the image forming apparatus 40, and therefore, the supporting brackets 113 protrude above a document glass 41 of the main body of the image forming apparatus 40.

Also, on a bottom wall 118 of the hinge body 110 opposite to the open portion 111 a, a spring support 117 protrudes to support a first end of a spring 122, which will be described later.

In addition, at a lower part of the front wall 114, a second protrusion 119 protrudes, and is coplanar with the bottom wall 118. When the hinge body 110 is moved out of the coupling hole 40 a, since the second protrusion 119 is caught by a hooking portion 42 disposed at one side of the main body of the image forming apparatus 40, as shown in FIG. 4, the release of the hinge body 110 from the coupling hole 40 a is prevented.

The pressure device 120 includes a pusher 121 and the spring 122, for a smooth pivoting of the hinge cam 130, since the pressure device 120 inhibits the pivoting of the hinge cam 130 pivotably supported by the supporting brackets 113. The pusher 121 is disposed to move downward and upward, to protrude outward through the open portion 111 a of the hinge body 110. The pusher 121 has locking protrusions 123 on opposing sides, positioned so that the locking protrusion 123 is inserted into the guide slots 112 a of the hinge body 110. Therefore, the pusher 121 moves upward and downward within the length of the guide slots 112 a, so that the pusher 121 is not released from the hinge body 110. The spring 122, that presses the pusher 121 toward the open portion 111 a, is disposed within the housing chamber 111. The first end of the spring 122 is supported by the spring support 117 of the hinge body 110, and a second end of the spring 122 is supported by a spring support 124 (see FIG. 4) positioned at a lower part of the pusher 121.

In assembling the pressure device 120, after the spring 122 is disposed in the housing chamber 111, the pusher 121 is connected to the hinge body 110. The pusher 121, which is elastically supported by the spring 121, has the locking protrusions 123, which contact upper sides of the guide slots 112 a. Assembly is simplified if a length of the spring 122 is substantially the same as a height from a bottom of the pusher 121 to the bottom wall 118 when the locking protrusions 123 contact the upper sides of the guide slots 112 a. In this case, as the pusher 121 is pushed into the housing chamber 111 to insert the locking protrusions 123 into the guide slots 112 a, a strain of the spring 122 does not occur. Accordingly, the user does not need to induce a strain pressure on the spring 122, which according to one aspect, has a high elastic stiffness. While described in terms of a spring 122, it is understood that other mechanisms can be used to bias the pusher 121, such as combinations of springs, hydraulic or pneumatic mechanisms, elastic materials, of other such devices.

In addition, according to one aspect, the pusher 121 is made of a lubricating resin, since there is a friction inherent in the sliding movement of the hinge cam 130. So-called “engineering plastics” can be used as the lubricating resin, such as polyethylene, polybutylene terephthalate, and polyamide.

The hinge cam 130 includes a body portion 131 connected to the cover 50 of the image forming apparatus, and a cam part 132 to slide in close contact with the pusher 121, under a predetermined pressure. The body portion 131 has a screw hole 131 a, and is combined with the cover 50 by inserting a fastening member, like a screw 60, into a boss portion 52 (see FIG. 4), through the screw hole 131 a, with one side of the body portion 131 being supported by a locking projection 51 (see FIG. 4) in the cover 50.

The cam part 132 is integrally combined to the body portion 131, and has a shaft hole 132 a. To put the hinge cam 131 in a condition ready to pivot on a hinge shaft 140, the cam part 132 is positioned in such a manner that the shaft hole 132 a of the cam part 132 is aligned with the shaft holes 113 a of the supporting brackets 113, and then the hinge shaft 140 is inserted into each shaft hole 113 a, 132 a.

A groove portion 140 a is positioned at one end of the hinge shaft 140. When the hinge shaft 140 is inserted into and passed through the shaft hole 132 a of the cam part 132 and the shaft holes 113 a of the supporting brackets 113, a coupling ring 141 is fixed to the groove portion 140 a. As a result, the hinge shaft 140 is prevented from releasing out of each shaft hole 113 a, 132 a.

As shown in FIG. 5, according to one aspect, a center C of the hinge shaft 140 is located at a predetermined interval toward a direction of the document glass 41 from a pressure central line L of the hinge cam 130 and the pusher 121. As a result, the pivot of the hinge cam 130 is more efficiently inhibited. According to one aspect, this allows, the spring 122 employed to be inexpensive, and have a low elastic modulus. In addition, according to one aspect, since there is friction inherent in the sliding movement of the pusher 121, the hinge cam 130 is made with a lubricating resin, such as polyethylene, polybutylene terephthalate, and polyamide.

Meanwhile, although the above embodiment of the present invention employs the hinge shaft 140 as a way to combine the hinge cam 130 to the hinge body 110, the present invention is not limited to this embodiment. Therefore, the hinge cam 130 can be pivotably connected to the hinge body 110 through various ways. For example, according to one aspect, although not shown in the drawings, protrusions are positioned at sides of the cam part 132 in the hinge cam 130, and the protrusions are inserted into the shaft holes 113 a of the supporting brackets 113.

Hereinafter, referring to the attached drawings, an operation of the hinge apparatus 100 according to an embodiment of the present invention is described in detail.

To insert the hinge apparatus 100 connected with the cover 50 into the coupling hole 40 a in the main body of the image forming apparatus 40, as shown in FIG. 4, the hinge body 110 is first tilted so that the second protrusion 119 can be inserted into the coupling hole 40 a in the main body of the image forming apparatus 40. Then, after moving the hinge body 110 to an upright position along a direction of arrow A, and inserting an end of the rear wall 115 of the hinge body 110 into the coupling hole 40 a, the hinge body 110 is pushed into the coupling hole 40 a. As the first protrusion 116 of the hinge body 110 contacts an upper side of the main body of the image forming apparatus 40, the cover 50 and the main body of the image forming apparatus 40 are coupled by the hinge apparatus 100. The cover 50 can secure a thin document such as a sheet of paper in tight contact with the document glass 41, as shown in FIG. 5.

In addition, to open the cover 50 and expose the document glass 41, as shown in FIG. 6, the cover 50 is pivoted and pushed over completely in a clockwise direction, and then the hinge cam 130 and the pusher 121 contact under the least pressure, since the spring is in a least compressed state. Then, if a document is positioned on the document glass 41 and the cover 50 is pivoted in a counterclockwise direction, the pivoting of the hinge cam 130 is inhibited, as the pressure between the hinge cam 130 and the pusher 121 increases continuously. As a result, the cover 50 closes slowly.

In the mean time, if a thick document, like a book, is positioned on the document glass 41, as shown in FIG. 7, the hinge body 110 is moved upward to an upper side of the coupling hole 40 a, to expand a space between the cover 50 in the closed position and the document glass 41. In a process of moving the hinge body 110 to the upper side of the coupling hole 40 a, the second protrusion 119 of the hinge body 110 is caught by the hooking portion 42 on the main body of the image forming apparatus 40. Consequently, the hinge body 110 is not released out of the coupling hole 40 a.

According to the embodiment of the present invention described above, there is an advantage that the hinge apparatus 100 can be implemented with a simple and easy assembly operation, since it is not a complicated structural connection among the component parts that compose the hinge apparatus 100.

Also, the hinge apparatus 100 can efficiently improve the usability of the image forming apparatus, since the hinge apparatus 100 decreases noise occurring when opening and closing the cover 50, and prevents the cover 50 from unintentionally closing.

While described as being used in an image forming apparatus, it is understood that the hinge apparatus 100 would be useful in other devices beyond image forming apparatuses, such as presses that compress various size items, cooking apparatuses, etc.

Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents. 

1. A hinge apparatus to open and close a scanner cover of an image forming apparatus in which the scanner cover is pivotably connected to a main body of the image forming apparatus so as to open and close a document glass, the hinge apparatus comprising: a hinge body inserted into a coupling hole provided in the main body of the image forming apparatus, the hinge body movable in an up and down direction in the coupling hole, the hinge body including a housing chamber having an upper side opening, and a pair of supporting brackets provided adjacent to the upper side opening; a hinge cam of which a portion is coupled to the scanner cover, and of which another portion is rotatably coupled to the supporting brackets of the hinge body; and a pressure device comprising a pusher disposed to slide in the housing chamber of the hinge body, a pressure spring applying pressure to the pusher such that an upper surface of the pusher is in contact with a facing surface of the hinge cam, wherein a locking protrusion protrudes from the pusher so as to prevent the release of the pusher from the housing chamber, the locking protrusion slidably engaging with a guide slot formed on the hinge body, the guide slot restricting an up and down sliding movement of the locking protrusion.
 2. The hinge apparatus of claim 1, wherein the hinge cam comprises: a body portion connected to the scanner cover; and a cam part connected to the body portion so as to pivot in contact with the pressure device.
 3. The hinge apparatus of claim 2, wherein the cam part and each of the supporting brackets are provided with a shaft hole, respectively.
 4. The hinge apparatus of claim 3, wherein a center of a hinge shaft is located toward the document glass compared to a pressure central line of the pressure device.
 5. The hinge apparatus of claim 1, wherein the hinge body comprises at least one first protrusion positioned at an area of the hinge body lower than the supporting brackets, to prevent the supporting brackets from entering the coupling hole.
 6. The hinge apparatus of claim 5, wherein the main body comprises a hooking portion positioned at an entrance of the main body of the image forming apparatus; and the hinge body comprises a second protrusion positioned at a bottom surface of the hinge body so as to be caught by the hooking portion, thereby preventing the release of the hinge body from the coupling hole when the hinge body is elevated.
 7. The hinge apparatus of claim 2, wherein the pusher and the hinge cam are made of a lubricating resin.
 8. The hinge apparatus of claim 1, wherein there are at least two pressure springs in the housing chamber.
 9. The hinge apparatus of claim 8, wherein the housing chamber comprises a spring support individually supporting the pressure springs.
 10. An image forming apparatus comprising: a main body having a document glass on which a document is placed; a scanner cover to open and close an upper side of the document glass; and a hinge apparatus pivotably supporting the scanner cover to the main body, wherein the hinge apparatus comprises: a hinge body inserted into a coupling hole provided in the main body of the image forming apparatus, the hinge body movable in an up and down direction in the coupling hole, the hinge body including a housing chamber having an upper side opening, and a pair of supporting brackets provided adjacent to the upper side opening; a hinge cam of which a portion is coupled to the scanner cover, and of which another portion is rotatably coupled to the supporting brackets of the hinge body; and a pressure device comprising a pusher disposed to slide in the housing chamber of the hinge body, a pressure spring applying pressure to the pusher such that an upper surface of the pusher is in contact with a facing surface of the hinge cam, wherein a locking protrusion protrudes from the pusher so as to prevent the release of the pusher from the housing chamber, the locking protrusion slidably engaging with a guide slot formed on the hinge body, the guide slot restricting an up and down sliding movement of the locking protrusion.
 11. The image forming apparatus of claim 10, wherein the hinge cam comprises: a body portion connected to the scanner cover; and a cam part connected to the body portion so as to pivot in contact with the pressure device.
 12. The image forming apparatus of claim 11, wherein the cam part and each of the supporting brackets are provided with a shaft hole, respectively.
 13. The image forming apparatus of claim 12, wherein a center of a hinge shaft is located toward the document glass compared to a pressure central line of the pressure device.
 14. The image forming apparatus of claim 10, wherein the hinge body comprises at least one first protrusion positioned at an area of the hinge body lower than the supporting brackets, to prevent the supporting brackets from entering the coupling hole.
 15. The image forming apparatus of claim 14, wherein the main body comprises a hooking portion positioned at an entrance of the main body of the image forming apparatus; and the hinge body comprises a second protrusion positioned at a bottom surface of the hinge body so as to be caught by the hooking portion, thereby preventing the release of the hinge body from the coupling hole when the hinge body is elevated.
 16. The image forming apparatus of claim 11, wherein the pusher and the hinge cam are made of a lubricating resin.
 17. The image forming apparatus of claim 10, wherein there are at least two pressure springs in the housing chamber.
 18. The image forming apparatus of claim 17, wherein the housing chamber comprises a spring support individually supporting the pressure springs.
 19. The hinge apparatus of claim 1, wherein: the hinge body comprises a first protrusion, to limit an amount that the hinge body moves into the coupling hole in the main body; the pressure device is formed as a single molded piece; and a top molded surface portion of the pressure device establishes direct contact with the hinge cam.
 20. The image forming apparatus of claim 10, wherein: the hinge body comprises a first protrusion, to limit an amount that the hinge body moves into the coupling hole in the main body; the pressure device is formed as a single molded piece; and the upper surface of the pusher is a top molded surface portion which establishes direct contact with the hinge cam.
 21. The hinge apparatus of claim 1, wherein: the hinge body comprises a first protrusion, to limit an amount that the hinge body moves into the coupling hole in the main body, and the supporting brackets are integrally formed with the hinge body and the supporting brackets are configured to rotatably support the hinge cam via a hinge shaft without employing an additional support structure reinforcing the supporting brackets.
 22. The image forming apparatus of claim 10, wherein: the hinge body comprises a first protrusion, to limit an amount that the hinge body moves into the coupling hole in the main body, and the supporting brackets are integrally formed with the hinge body and the supporting brackets are configured to rotatably support the hinge cam via a hinge shaft without employing an additional support structure reinforcing the supporting brackets.
 23. The hinge apparatus of claim 1, wherein: the cam part has a hinge shaft; and a center of rotation of the hinge shaft is offset by a predetermined distance from a line along which a center of the pressure device moves so that rotation of the hinge cam is inhibited when the pressure device moves.
 24. The hinge apparatus of claim 23, wherein the center of rotation of the hinge shaft is located at the predetermined distance in a direction toward the document glass from the center line of the pressure device.
 25. The image forming apparatus of claim 10, wherein: the hinge cam has a hinge shaft; and a center of rotation of the hinge shaft is offset by a predetermined distance from a line along which a center of the pressure device moves so that rotation of the hinge cam is inhibited when the pressure device moves.
 26. The image forming apparatus of claim 25, wherein the center of rotation of the hinge shaft is located at a predetermined distance in a direction of toward the document glass from the center line of the pressure device.
 27. The hinge apparatus of claim 1, wherein a first end of the pressure spring is supported by a first spring support of the hinge body, and a second end of the pressure spring is supported by a second spring support positioned at a lower part of the pusher.
 28. The image forming apparatus of claim 10, wherein an upper end of the pressure spring is supported by a spring support provided on the pusher.
 29. The image forming apparatus of claim 10, wherein a lower end of the pressure spring is supported by a spring support provided on the hinge body.
 30. A hinge apparatus to open and close a cover of an image forming apparatus, which pivotally connects the cover to a main body of the image forming apparatus, the hinge apparatus comprising: a hinge body comprising a housing chamber and supporting brackets; a hinge cam, coupled to the cover, pivotably connected to the supporting brackets; and a pressure device disposed at the hinge body to press the hinge cam, said pressure device comprising: a pusher comprising a guide member, disposed in the housing chamber; and a spring disposed in the housing chamber to press the pusher, wherein the hinge body is provided with a receiving member corresponding to the guide member to guide a movement of the pusher.
 31. The hinge apparatus of claim 30, wherein: the main body has a coupling hole; the hinge body comprises a first protrusion, to limit an amount that the hinge body moves into the coupling hole in the main body; the pressure device is formed as a single molded piece; and a top molded surface portion of the pressure device establishes direct contact with the hinge cam.
 32. The hinge apparatus of claim 30, wherein: the main body has a coupling hole; the hinge body comprises a first protrusion, to limit an amount that the hinge body moves into the coupling hole in the main body, and the supporting brackets are integrally formed with the hinge body and the supporting brackets are configured to rotatably support the hinge cam via a hinge shaft without employing an additional support structure reinforcing the supporting brackets.
 33. The hinge apparatus of claim 30, wherein: the hinge cam has a hinge shaft; and a center of rotation of the hinge shaft is offset by a predetermined distance from a line along which a center of the pressure device moves so that rotation of the hinge cam is inhibited when the pressure device moves.
 34. The hinge apparatus of claim 33, wherein: the cover opens and closes an upper side of the document glass; and the center of rotation of the hinge shaft is located at the predetermined distance in a direction toward the document glass from the center line of the pressure device.
 35. The image forming apparatus of claim 30, wherein an upper end of the pressure spring is supported by a spring support provided on the pusher.
 36. The image forming apparatus of claim 30, wherein a lower end of the pressure spring is supported by a spring support provided on the hinge body.
 37. A hinge apparatus to open and close a cover of an image forming apparatus, which pivotally connects the cover to a main body of the image forming apparatus, the hinge apparatus comprising: a hinge body comprising a housing chamber and supporting brackets; a hinge cam, coupled to the cover, pivotably connected to the supporting brackets; and a pressure device disposed at the hinge body to press the hinge cam, said pressure device comprising: a pusher comprising a guide member, disposed in the housing chamber; and a spring disposed in the housing chamber to press the pusher, wherein the hinge body is provided with a receiving member corresponding to the guide member to guide a movement of the pusher, wherein the hinge cam has a hinge shaft, and a center of rotation of the hinge shaft is offset by a predetermined distance from a line along a center of the pressure device.
 38. The hinge apparatus of claim 37, wherein: the main body has a coupling hole; the hinge body comprises a first protrusion, to limit an amount that the hinge body moves into the coupling hole in the main body; the pressure device is formed as a single molded piece; and a top molded surface portion of the pressure device establishes direct contact with the hinge cam.
 39. The hinge apparatus of claim 37, wherein: the main body has a coupling hole; the hinge body comprises a first protrusion, to limit an amount that the hinge body moves into the coupling hole in the main body; and the supporting brackets are integrally formed with the hinge body and the supporting brackets are configured to rotatably support the hinge cam via the hinge shaft without employing an additional support structure reinforcing the supporting brackets.
 40. The hinge apparatus of claim 37, wherein: the cover opens and closes an upper side of a document glass of the image forming apparatus; and the center of rotation of the hinge shaft is located at the predetermined distance in a direction toward the document glass from the center line of the pressure device. 